Cone adaptor for ball joint studs, tie rods, sway bar links and the like

ABSTRACT

A ball joint assembly for a vehicular steering or suspension application includes a cap-like housing in which is captured the articulating ball portion of a stud. A shank extends from the ball portion, outwardly from the housing cap, to provide a connection and anchoring interface for the suspension member or other anchoring component. The connection interface with the anchoring suspension member is characterized by a specially designed surface which is convenient to machine, provides increased surface-to-surface contact area, and provides additional advantages such as improved stress distribution and NVH benefits. A washer-like cone adaptor mates with a specially formed adaptor interface region on the stud. On its outer surface, the adaptor has a broad tapering feature designed to seat in a complementary-shaped receiving flare in the anchoring suspension member. The mating contact region between the adaptor and the stud is formed with spherical or spheroidal curvatures, or by single or multiple step configurations.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 11/533,186, filed Sep. 19, 2006, which is incorporated herein byreference in its entirety, which claims priority to U.S. ProvisionalApplication No. 60/718,708, filed on Sep. 20, 2005, also incorporatedherein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a ball and socket type joint of the type usedin vehicular steering and/or suspension applications, and moreparticularly toward such a ball joint assembly for use in applicationswhere one of the anchoring members, such as a steering knuckle or tierod for example, is made from a relatively soft material like aluminum.

2. Related Art

Ball joints are typically used in vehicular applications wherethree-dimensional movement of a wheel, and in particular a steerablewheel, is required when a vehicle is turning and the suspension isaccommodating movement over rough terrain. In the normal course ofoperation, ball joints are subjected to very high stresses. Thesestresses are transmitted through the stud of a ball joint assembly intothe suspension member, which may be a steering knuckle, control arm,steering link, frame member or other feature.

The recent emphasis on reducing vehicular weight is driving materialselections toward lighter options. Sometimes, there is a motivation tosubstitute aluminum for traditional cast iron materials, even in thearea of chassis and suspension components. Unfortunately, lightermaterials are often softer than the heavier materials they replace, andtherefore less suited to endure the localized and concentrated stresseswhich may arise during normal vehicular operations.

FIGS. 9 and 10 illustrate two different prior art attempts to accomplishsimilar functionality for ball joint assemblies, and in particular studswhich are intended to be anchored in relatively soft material likealuminum. FIG. 9, in particular, is intended to correspond to the designdepicted in U.S. Pat. No. 6,527,468, the entire disclosure of which ishereby incorporated by reference. These designs are either difficult toproduce on a high volume basis, or result in unacceptable attributessuch as NVH issues and provide less surface-to-surface contact in theinterface regions. By contrast, the subject invention as depicted invarious embodiments in FIGS. 1-8, overcomes some or all of these issuesand represents a significant improvement over prior art constructions.

Accordingly, there is a need for an improved method of interconnecting aball joint assembly to vehicular steering and suspension features toaccommodate the anchor points being made from a softer material.

SUMMARY OF THE INVENTION

The subject invention comprises a ball and socket joint assembly of thetype used in vehicular steering and suspension applications in which ananchoring and control member is made from relatively soft material. Theassembly comprises a stud having a ball portion on one end thereof and ashank extending therefrom. The shank includes a thread form forattaching the stud to an anchoring control member made from a relativelysoft material. The shank includes an adaptor interface region betweenthe ball portion and the thread form. An annular, loose piece adaptor isslidably disposed on the shank and matingly engages the adaptorinterface region in abutting surface-to-surface contact therewith. Theadaptor has a frustoconical exterior surface tapering inwardly towardthe thread form, and an interior surface. The interior surface of theadaptor includes a generally spheroidal female surface configuration andthe adaptor interface region of the shank has a complementary-shapedgenerally spheroidal male surface configuration. The generallyspheroidal female and male mating surfaces provide enhanced stressdistributions and load carrying capabilities with less adaptor-to-shankslippage in operation.

According to another aspect of the invention, a ball and socket jointassembly is provided of the type used in vehicular steering applicationsin which an anchoring control member is made from relatively softmaterial. A stud has a ball portion on one end thereof and a shankextending therefrom. The shank includes a thread form for attaching thestud to an anchoring control member made from a relatively softmaterial. The shank includes an adaptor interface region between theball portion and the thread form. An annular, loose piece adaptor isslidably disposed on the shank and matingly engages the adaptorinterface region in abutting surface-to-surface contact therewith. Theadaptor has a frustoconical exterior surface tapering inwardly towardthe thread form, and an interior surface. The interior surface of theadaptor includes a generally cylindrical major side wall establishing amajor inside diameter thereof and a generally cylindrical minor sidewall, concentric with the major side wall, establishing a minor insidediameter thereof. The interior surface of the adaptor also includes atleast one annular shoulder between the major and minor side walls. Theadaptor interface region of the shank includes a generally cylindricalmajor shaft matingly received with the major side wall of the adaptor, aminor shaft matingly received within the minor side wall of the adaptor,and at least one annular shoulder between the major and minor shafts.The shoulder of the adaptor is pressed in face-to-face contact with theshoulder of the shank.

Both aspects of the invention as set forth herein overcome theshortcomings and disadvantages present in prior art designs, byproviding an improved construction for interconnecting a ball jointassembly to a vehicular steering and/or suspension feature toaccommodate anchor points made from a softer material.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention willbecome more readily appreciated when considered in connection with thefollowing detailed description and appended drawings, wherein:

FIG. 1 is a perspective view of an exemplary application for the subjectball and socket joint assembly wherein the steering knuckle is supportedbetween upper and lower control arms made from a relatively softmaterial such as aluminum;

FIG. 2 is a cross-sectional view taken generally along lines 2-2 in FIG.1;

FIG. 3 is a front elevation view of a stud according to the subjectinvention showing an annular, loose piece adaptor operatively disposedthereon and depicted in cross-section;

FIG. 4 is a perspective view of the annular, loose piece adaptor shownin quarter section;

FIG. 5 is a view as in FIG. 3 but depicting a first alternativeembodiment of the geometric surface formations between the female andmale mating surfaces of the stud and the adaptor;

FIG. 6 is a view as in FIG. 3 but showing a second alternativeembodiment for the mating interface between the stud and adaptor;

FIG. 7 is a view as in FIG. 3 but depicting a third alternativeembodiment of the adaptor interface region;

FIG. 8 is a view as in FIG. 3 but illustrating a fourth alternativeembodiment of the abutting surface-to-surface contact region between theadaptor and the stud;

FIG. 9 is a depiction of a prior art style stud and adaptorconfiguration; and

FIG. 10 is another depiction of a prior art stud and adaptorconfiguration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the Figures, wherein like numerals indicate like orcorresponding parts throughout the several views, a vehicular steeringand suspension assembly such as used in the front, dirigible wheels of amotor vehicle is generally shown at 12 in FIG. 1. Although the frontsuspension system 12 is shown here comprising upper 14 and lower 16control arms interconnecting a steering knuckle 18, it will beappreciated by those of skill in the art that the contemplated inventionmay find application in other steering and/or suspension components. Forexample, the invention, as will be described in multiple embodiments,may be deployed in not only steering knuckles and control arminterfaces, but also in steering linkages, frame member connections, andother articulating features.

Returning to the illustrative application depicted in FIG. 1, asuspension system 12 is shown including a combined spring and dampeningdevice 20 interconnecting the lower control arm 16 to interposingportions of the vehicle chassis or frame (not shown). The steeringknuckle 18 includes a spindle 22 upon which a vehicular wheel assembly24 is mounted, together with appropriate braking and bearing componentsas is well known to those of skill in this art. A steering arm 26extends transversely from the steering knuckle 18, ready to connect withan appropriate steering link (not shown). Although purely depicted forits illustrative value in FIG. 1, the steering suspension system 12 inthis example includes components made from relatively soft material suchas aluminum or other light-weight materials or alloys, as compared withthe traditional steel and cast iron constructions. For example, thelower control arm 16 in this example is made from aluminum or analuminum alloy having material properties and characteristics which aresofter and more ductile than traditional iron and steel constructions.The suspension system 12 includes, in this example, a pair of ball jointassemblies, generally indicated at 28, interconnecting the upper 14 andlower 16 control arms to the steering knuckle 18, respectively.

FIG. 2 represents a cross-sectional view of the ball joint assembly 28as taken through the lower control arm 16. Here, the ball joint assembly28 is shown including a stud, generally indicated at 30, having a ballportion 32 at one end thereof. A shank 34 extends from the ball portion32, and includes a thread form 36 for attaching the stud 30 to ananchoring control member made from a relatively soft material, which inthis case is the lower control arm 16. A washer 38 and nut 40 areadvanced onto the thread form 36 for establishing the requisite tensilestress through the stud 30 to maintain a secure connection to the lowercontrol arm 16 in use.

A housing cap 42 surrounds the ball portion 32 of the stud 30 forproviding an articulating interface therewith. The housing cap 42, whileshown in but one purely exemplary configuration in FIG. 2, is seated viaa press fit operation into a corresponding receiving pocket in thesteering knuckle 18. A polymer liner 44 may, in some circumstances, beinterposed between the housing cap 42 and the ball portion 32 as abearing surface. A resilient dust boot 46 is shown extending between thehousing cap 42 and the shank 34 for preventing contaminant infiltrationinto the articulating interface. Of course, many other constructions anddesigns of the housing cap 42 and other components such as the dust boot46 may be implemented in conjunction with the novel features of thisinvention. It is necessary only that the housing cap 42 complement theball portion 32 and thereby provide a full articulating joint whichfacilitates the three-dimensional movement necessary to accommodatewheel turning, suspension travel, and other mechanical linkagemovements.

Referring now to FIGS. 3 and 4, the stud 30 portion of the ball jointassembly 28 is shown including an adaptor interface region 48 betweenthe ball portion 32 and the thread form 36. An imaginary central axis Ais shown as a center-line for the various surface features formed as abody of revolution. The adaptor interface region 48 includes numeroussurface features and contours including a generally cylindrical collar50 which, among other functions, may serve to receive the clamped lowerend of the dust boot 46, as depicted in FIG. 2. In addition, the adaptorinterface region 48 includes a generally spheroidal male surfaceconfiguration 52 formed in the concave direction. Thus, the spheroidalmale surface configuration 52 takes the appearance of an enlarged fillettransitioning the collar 50 down toward the thread form 36.

The adaptor interface region 48 of the shank 34 is designed to receivean annular, loose piece adaptor, generally indicated at 54. The adaptor54 is slidably disposed over the shank 34 and matingly engages theadaptor interface region 48 in abutting surface-to-surface contacttherewith. The adaptor 54 has a frustoconical exterior surface 56tapering inwardly toward the thread form 36. Thus, as shown in FIG. 2,the frustoconical exterior surface 56 of the adaptor 54 seats within acomplementary shaped flare 58 in the lower control arm 16. Therelatively shallow taper presented by the frustoconical exterior surface56 of the adaptor 54 accommodates a distribution of loading stressesover a wider area of the lower control arm 16. This thereby reduces thepressure applied to the anchoring lower control arm 16 via the tightenednut 40. By reducing the contact pressure in this manner, the use ofsofter material such as aluminum and alloys thereof for the lowercontrol arm 16, or other suspension member or linkage, can be enabled.

The adaptor 54 also includes an interior surface, opposite thefrustoconical exterior surface 56, which is characterized in thisembodiment by a generally spheroidal female surface configuration 60.The spheroidal female configuration 60 complements the spheroidal maleconfiguration 52 of the shank 34 and establishes an abuttingsurface-to-surface contact therewith. The spheroidal femaleconfiguration 60 is shown in the convex direction, and cooperatestogether with the mating male surface to provide enhanced stressdistributions and load carrying capabilities for the ball joint assembly28. The spherical or spheroidal surface curvatures also facilitate lessadaptor-to-shank slippage in operation. The surface configurations areconducive to manufacturability, and also provide other benefits such asenhanced NVH characteristics and the like. The interior surface of theadaptor 54 further includes a generally cylindrical side wall 62adjacent its generally spheroidal female surface configuration 60. Theside wall 62 matingly receives a lower portion of the collar 50 of theshank 34, and provides enhanced seating and radial stress distributionsbetween the two components.

Referring now to FIG. 5, a first alternative embodiment of the subjectinvention is depicted, wherein like or corresponding parts are depictedusing the same reference characters with the prefix “1.” In thisembodiment, the adaptor 154 is identical in every respect to thatdescribed previously in connection with the preferred embodiment, butthe side wall 62 is omitted. In this case, the spheroidal femaleconfiguration 60 receives 100% of the axial and radial loading vectorsbetween the adaptor 154 and the stud 30. In some applications, thisdesign may be preferred.

Turning now to FIG. 6, a second alternative embodiment of the subjectinvention is depicted, wherein like or corresponding parts to thosedescribed above are indicated using the same reference numerals togetherwith the prefix “2.” In the embodiment of FIG. 6, the interior surfaceof the adaptor 254 is characterized by the generally spheroidal femalesurface configuration 260 having a generally concave formation, whereasthe mating, generally spheroidal, male surface configuration 252 on theadaptor interface region 248 has a generally convex formation. Thus, itcan be seen that FIG. 6 represents a mere reversal of concave and convexfeatures in the surface contact regions between the adaptor 254 and theadaptor interface region 248. Accordingly, similar performancecharacteristics can be expected.

In FIG. 7, a third alternative embodiment of the subject invention isdepicted. In this example, like or corresponding parts to thosepreviously presented are shown with like reference numerals preceded bythe prefix “3.” In this example, generally spheroidal interface surfacesbetween the adaptor 354 and the adaptor interface region 348 aresubstituted with one or more step configurations. A single stepconfiguration is illustrated in FIG. 7, wherein the interior surface ofthe adaptor 354 includes a generally cylindrical major side wall 362establishing a major inside diameter. A generally cylindrical minor sidewall 364, concentric with the major side wall 362, establishes a minorinside diameter of the adaptor 354. At least one annular shoulder 366extends between the major 362 and minor 364 side walls, therebyproviding a ledge generally perpendicular to the central axis A. Theshoulder 366 therefore establishes a contact surface through which allaxially vectored stresses are transferred between the adaptor 354 andthe stud 30. The adaptor interface region 348 of the shank 334 includesa generally cylindrical major shaft corresponding to the collar 350.This major shaft is matingly received within the major side wall 362 ofthe adaptor 354. The adaptor interface region 348 also includes a minorshaft 368 that is matingly received within the minor side wall 364 ofthe adaptor 354. An annular shoulder 370 extends between the major 350and minor 368 shafts to establish a generally transverse ledge, relativeto the central axis A. The shoulder 370 is adapted to seat inface-to-face contact with the shoulder 366 of the adaptor 354.

FIG. 8 depicts a fourth alternative embodiment of the subject inventionwherein like or corresponding parts to those described above arereiterated but with the prefix “4” for convenience. In this example, apair of progressively sized steps are machined or otherwise formed onthe adaptor interface region 448, with complementary receiving shapesformed on the inner surface of the adaptor 454. More specifically, theinterior surface of the adaptor 454 is shown herein including agenerally cylindrical intermediate side wall 472 that is concentricallydisposed relative to the major side wall 462 and thereby establishing anintermediate sized diameter. The intermediate side wall 472 bisects theshoulder 466 into plural segments. The adaptor interface region 448 ofthe shank 434 likewise includes a generally cylindrical intermediateshaft bisecting the shoulder 470 into plural segments. The intermediateshaft 474 matingly engages the intermediate side wall 472 of the adaptor454. Thus, as can be seen upon consideration of FIG. 8, themulti-stepped configuration of the mating surfaces increases theintegrity of fit between the adaptor 454 and the stud 430. Of course,additional steps can be incorporated into the design, as cancombinations of steps together with the spheroidal curvatures depictedin FIGS. 2-6.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. For example, more stepscan be formed in the interface portion, and the step configuration canbe combined with spheroidal curvatures. It is, therefore, to beunderstood that the invention may be practiced otherwise than asspecifically described.

1. A ball and socket joint assembly of the type used in vehicularsteering and suspension applications in which an anchoring controlmember is made from relatively soft material, said assembly comprising:a stud having a ball portion on one end thereof and a shank extendingtherefrom, said shank including a thread form for attaching said stud toan anchoring control member made from a relatively soft material; saidshank including an adaptor interface region between said ball portionand said thread form; an annular, loose piece adaptor slidably disposedon said shank and matingly engaging said adaptor interface region inabutting surface-to-surface contact therewith, said adaptor having aninterior surface and a frustoconical exterior surface tapering inwardlytoward said thread form; said interior surface of said adaptor includinga generally cylindrical major side wall establishing a major insidediameter thereof and a generally cylindrical minor side wall, concentricwith said major side wall, establishing a minor inside diameter thereof,and at least one annular shoulder between said major and minor sidewalls; and said adaptor interface region of said shank including agenerally cylindrical major shaft matingly received within said majorside wall of said adaptor, a minor shaft matingly received within saidminor side wall of said adaptor, and at least one annular shoulderbetween said major and minor shafts, said shoulder of said adaptorpressed in face-to-face contact with said shoulder of said shank.
 2. Theassembly of claim 1 wherein said interior surface of said adaptorincludes a generally cylindrical intermediate side wall concentric withsaid major side wall establishing an intermediate inside diameter, saidintermediate side wall bisecting said shoulder into plural segments. 3.The assembly of claim 2 wherein said adaptor interface region of saidshank includes a generally cylindrical intermediate shaft bisecting saidshoulder thereof into plural segments, said intermediate shaft matinglyengaging said intermediate side wall of said adaptor.
 4. The assembly ofclaim 1 further including a housing cap surrounding said ball portion ofsaid stud and articulatable thereabout.
 5. The assembly of claim 4further including a resilient dust boot extending between said housingcap and said shank for preventing contaminant infiltration into thearticulating interface.